1. Field of the Invention
The present invention generally relates to vehicle wheels that are equipped with an attached chromium-plated wheel cover, cladding or overlay. The metal plated overlay's bond strength permits the overlay to be shaped and contoured on to the shape of the wheel, so as to maximize aesthetic effects.
2. Description of the Related Art
Automotive vehicles often include substantial amounts of metal-plated trim elements that provide both decorative and functional features. These decorative elements are widely used to enhance the aesthetic appearance of automotive wheels. In addition, an overlay not only improves the appearance of unadorned standard steel wheels, but is also used with cast aluminum wheels, which are known to be expensive and difficult to plate with chromium. Below, numerous structural approaches for combining overlays with steel and/or cast wheels are described and divided into first and second groups of prior art.
In the first group, U.S. Pat. No. 5,636,906 to Chase, owned by the assignee hereof, teaches a decorative overlay to enhance the aesthetic appearance of an automotive wheel. The overlay described in the preferred embodiment is a metal-plated plastic panel that is adhesively attached to the outboard surface of the wheel disk and may radially extend to the flange lip of a typical rim flange complying with the tire and wheel association standards so as to cover the outboard surface in the rim flange area of the wheel. The overlay provides a pleasing aesthetic effect to the wheel. The overlay covers most of the wheel's outboard surface but does not extend radially outward to cover the edge or flange lip of the standard rim flange of the wheel. The base material composition and metal plating of the overlay permit the exterior surface of the overlay to be closely contoured to the outboard surface of the wheel, namely, the disk of the wheel and a major portion or all of the standard rim flange of the wheel. Further, the overlay resists delamination of the metal plating due to heat.
A further example of a vehicle wheel having a permanently secured wheel cover is disclosed in U.S. Pat. No. 5,368,370 to Beam. Here, a chrome-plated stainless steel cladding or wheel cover includes an outer peripheral edge that is forced into engagement with the wheel within a groove formed in a typical rim flange, complying with the tire and rim association standards, along the outboard surface of the wheel. This engagement locates and holds the wheel cover in place while the adhesive cures. Since the groove is machined in the rim flange axially inboard of the edge or flange lip of the rim flange the overlay extends outward to, but does not cover the lip of the standard rim flange of the wheel. Similarly, Maloney et al., U.S. Pat. No. 5,435,631, teach a wheel cover retention system, wherein the outboard tire bead seat retaining flange or standard rim flange of the wheel includes a groove as taught in Beam for securing the wheel cover to the wheel. Again, this overlay extends outward to, but does not cover the flange lip of the standard rim flange of the wheel.
Additionally, a wheel cover that extends outward to the flange lip of the standard rim flange of a wheel was a subject of a recently issued patent owned by the assignee hereof. Chase, U.S. Pat. No. 5,564,791, teaches an overlay that extends radially outward to—but not covering—the flange lip of the rim flange of the wheel. Furthermore, this overlay is configured with the wheel to enable a standard balance weight to be secured to the rim flange of the wheel.
Finally, U.S. Pat. No. 5,842,750 to Murray et al. teaches a composite styled wheel molded in situ having a mold-formed outer edge. Murray et al. disclose a urethane foam wheel cover molded in situ and permanently affixed to the outboard surface of a wheel, wherein the urethane material extends from fastener holes in the disk of the wheel radially outwardly to cover at least a portion of an outboard standard flange edge of the wheel. Murray et al. thereby teach eliminating the prior art requirement of trimming offal formed at an outboard flange edge of the wheel in a mutli-step cutting process that results in exposing an interior cellular construction of the urethane foam.
Unfortunately, there are several problems with using a molded in situ urethane cover for a wheel. First, urethane material molded in situ directly to the outboard surface of a wheel is susceptible to degradation in quality under localized high heat applications. Urethane material will tend to break down in localized high temperatures experienced in the wheel hub area of the wheel disk under certain actual road conditions. This is particularly true in the immediate region of the wheel hub where temperatures tend to be much higher than in the outer periphery of the wheel. Further, it is understood by those skilled in the art that one reason for spacing a plastic wheel cover from the outboard wheel surface is to avoid the deleterious effects of heat generated into the disk of the wheel by the brake system, that would otherwise distort or melt the plastic wheel cover and/or delaminate any surface treatment, i.e. paint, plating, etc., applied thereto. Second, those skilled in the art also appreciate that completely filling a wheel cavity with urethane is disadvantageous in that doing so does not readily permit limiting the degree to which the urethane fills the cavity causing localized inclusions affecting wheel weight, balance and fuel economy. In other words, in situ molding a wheel cover requires a relatively large volume of expensive urethane material. Third, an additional problem associated with the manufacturing method taught by Murray et al. is that a supply of wheels must be readily and continuously available to the manufacturer for molding of the wheel cover to the wheel, rendering a manufacturing process that is somewhat complicated, expensive, and reliant upon the continuous availability of wheels, which may be impractical for just-in-time manufacturing programs. Finally, and most significantly, the plastic foamed urethane overlay taught by Murray et al. dictates a variable thickness that is wedge-shaped in cross section at the standard outboard rim flange edge of the wheel. Accordingly, the radially outermost portion of the plastic urethane overlay will be extremely thin and therefore unreliable as extremely susceptible to chipping, thereby resulting in an unacceptable surface treatment aesthetically speaking.
In each of the above prior art references, it is evident that the overlay covers only most of the outboard face of the wheel and does not reliably cover the flange lip of the rim flange at the outer extremity of the standard rim flange. Accordingly, the exposed flange lip is susceptible to damage from stone chips resulting in bare metal exposed to the ambient elements i.e. salt, mud, water, etc. Additionally, the stainless steel overlay disclosed in both Beam and Maloney et al. is highly susceptible to visible “red rust” corrosion around the periphery. This is because, at the interface where the cover is mounted in the groove in the standard rim flange, galvanic action between the stainless steel overlay and a hot roll steel wheel can result in deposits of unattractive corrosion at the interface. Further, the exposed flange lip of the standard rim flange of the wheel circumscribing the periphery of the overlay is a clear manifestation that this is a cladded wheel and tends to make the wheel look smaller. This exposure of the flange lip of the standard rim flange completely fails to meet the objective; that is, to provide a visible impression to the consumer that this is a one-piece wheel, whereby the entire visible outboard surface of the overlay appears to be the entire outboard surface of the wheel, and not a separate attachment. Wheel and wheel cover tolerances may stack up to yield noticeable eccentricity between the wheel cover and wheel. For instance, where one arcuate sector of the wheel's outboard surface at the radially outer periphery of the wheel may be adequately covered by the wheel cover, an opposite arcuate sector may be insufficiently covered, thereby yielding an obvious nonsymmetrical appearance (not chrome plated) and a wheel cover/wheel assembly that is aesthetically unacceptable. Additionally, the exposed flange lip of the standard rim flange of the wheel along the radially outer periphery of the rim flange of the overlay also tends to make the wheel look smaller and less robust to the consumer. In contrast to this first group of prior art, the second group of prior art below addresses wheel trim that extends beyond the periphery of the flange lip of the standard rim flange of the wheel.
For example, Reppert, U.S. Pat. No. 4,275,931, and Bowling, U.S. Pat. No. 4,348,061, both teach a wheel trim ring that snaps onto the standard rim flange to extend beyond the flange lip of the rim flange. Similarly, U.S. Pat. No. Re. 35,497 to Carter, III teaches a retention system for a decorative simulated wheel cover wherein the wheel cover clearly extends radially beyond an outer peripheral edge of the standard rim flange of the wheel. Additionally, Polka, U.S. Pat. No. 5,358,313, teaches an adjustable wheel liner for truck wheels wherein the cover extends well over the lip.
Todd, U.S. Pat. No. 5,143,426, teaches a standard vehicle wheel construction that eliminates the need to use an adhesive to secure a cover assembly to a wheel. Todd discloses that the cover assembly has a molded polystyrene base applied to an outboard surface of the wheel, with an ornamental thermoplastic fascia coat covering the base. The fascia coat is mechanically locked through the use of a mechanical interference with the periphery of the vent openings in the wheel to prevent separation of the wheel cover from the wheel. Todd also discloses that a peripheral edge of the fascia extends to an edge of the wheel, but does not disclose or teach any further detail for this feature. It is ambiguous from the drawings whether Todd discloses that the fascia extends to an axial edge or a radial edge of the wheel. In the perspective views of FIGS. 1 and 2, the fascia appears to extend to the axial edge of the wheel but beyond the radial edge of the wheel; whereas in the cross-sectional views of FIGS. 4a and 4b, the radial edge of the fascia appears to be in line with the radial edge of the wheel. Therefore, the disclosure of Todd is unclear as to exactly what is disclosed in regard to fascia overlap conditions with the underlying wheel's structural features.
Hodge et al., U.S. Pat. No. 5,346,288, teach a continuous cushioning member interposed laterally between a plastic wheel cover and a wheel, so as to avoid noise between the plastic cover and the steel wheel. Hodge et al. disclose that an outer peripheral portion of the cover overlies an outward turned flange portion of the wheel and is positioned in lateral proximity thereto. Like Todd, Hodge et al. does not provide sufficient disclosure with respect to the radially outer peripheral overlap of the cover to the underlying structural elements of the wheel. Because the overlapping relationships appear to be nearly co-diametrical but are nonetheless unclear, and because there is no disclosure to the contrary, it can only be reasonably presumed that the covers of Todd and Hodge et al. and the rim flanges of the wheel comply with the tire and wheel association standards.
An alternate approach to solving the problems of the first group of prior art involves not only extending the overlay beyond the radially outer periphery of the wheel, but actually wrapping the overlay around the flange lip of the standard rim flange of the wheel. For example, Beith, U.S. Pat. No. 3,726,566, teaches that the edge of the cover is formed to grip over and around the edge of the standard terminal flange of the wheel, to aid in fixing the wheel cover to the wheel. Heck et al., U.S. Pat. No. 5,595,423, and Eikhoff, U.S. Pat. No. 5,829,843, disclose similar teachings. Heck et al. disclose the use of a stainless steel overlay that covers at least a portion of the outboard facing disk of the wheel and the entire portion of the outer peripheral flange lip of the outboard bead seat retaining flange or standard rim flange. The overlay is preferably formed from stainless steel, is adhesively attached to the wheel, and has an appropriate decorative surface on its outboard side. This adhesive is applied on the outboard face of the wheel disk in a predetermined pattern, so that when the wheel cover is installed on the disk, a smearing of the adhesive occurs over substantially the entire outboard face of the disk. Since the adhesive covers substantially the entire interface between the wheel cover and the disk, it is effective to provide a seal and prevent water, mud, salt and other debris from entering between the wheel cover and the outboard surface of the wheel disk. At the outer peripheral edge of the standard rim flange facing the tire is a smooth, rounded outer peripheral end and a circumferential, radially outwardly facing groove. The peripheral end and the groove are both formed by machining operations to a predetermined specification. The groove is formed along the inboard side of the tire bead-seat retaining flange or standard rim flange. The outer peripheral end portion of the wheel cover is assembled to the smooth, rounded outer peripheral end of the wheel and terminates in the radially outwardly facing groove adjacent the rubber tire. However, this technology, like the prior art above, has several problems.
Accordingly, there is at least one unique problem with the Heck et al. '423 patent. For example, in assembling the wheel cover to the wheel, it is clear that overbend is required to accommodate the natural springback of the radial end of the stainless wheel cover. This overbend results in frictional engagement of the outer peripheral edge of the wheel cover with the smooth, rounded outer peripheral end of the wheel. This frictional engagement results in the removal of any form of protective coatings that may be on the wheel. Removal of the protective coating causes the wheel material to be in direct contact with the stainless overlay, and thereby detrimental galvanic action between the stainless steel cover and the rim flange will occur over time. There are more problems with this reference that are shared with the second group of prior art, and are described below.
The second group of prior art references address some of the concerns with the exposed flange lip of the standard rim flange existing in the first group of prior art references, but fails to address several other problems. Tire servicing, radial load deflections during operation, and “run flat” conditions are all situations in which permanent damage to the overlay or tire will occur. During tire installation and removal, service equipment that locates on the extreme periphery of the standard rim flange of the wheel will damage the prior art wheel covers that wrap around the flange lip of the rim flange. This will occur where the outermost diameter of the wheel cover is greater than that of the outermost diameter of the wheel, and could occur if the peripheral flange of the overlay is not located net against the flange lip of the standard rim flange of the wheel. Similarly, where the outside diameter of the wheel cover is greater than that of the wheel, it is likely that many wheel covers of the prior art would become damaged upon installation or removal of balance weights. Further, a larger diameter cladding is more likely to be cracked or chipped during a vehicle impact with a curb or a pothole, or as a result of material handling in the production process when outer diameters of assembled wheels collide into one another such as occurs on a gravity feed conveyor. Also, if a wheel and cladding assembly without a tire is rolled along a surface, the surface treatment of the cover (chrome plating) will chip since the cover wraps around the outside diameter of the wheel.
An additional problem with overlays which wrap around the rim flange is that the wheel and chrome plated overlay assembly appear to look larger relative to the width of the black rubber of a tire and therefore the overall aesthetics of the vehicle are affected. Wrapping the overlay around the standard rim flange of the wheel does indeed result in an overall diameter of the wheel assembly that is larger than the outer diameter of the wheel only. The only way to solve this problem is to reduce the outer diameter of the wheel before the overlay is attached to it so that when the overlay wraps around the standard rim flanges of a reduced diameter wheel the resulting assembly has the same diameter as the original design intent. Such solution is not tolerable since it affects the structural integrity of the wheel as well as significantly increases the costs of producing the wheel only.
Additionally, radial tire loads distort and deflect the standard rim flange area of the wheel during vehicle operation, as is known in the art. Because the prior art overlay actually wraps around the deflecting flange lip and standard rim flange, the deflections will in turn deflect the overlay resulting in cracking of the chromium plated surface layer. Further, these deflections of the overlay may cause the overlay's peripheral edge to become unseated from the groove or separate from the wheel. This is particularly a problem where the overlay's peripheral edge normally lies in a groove in the rim flange next to the rubber tire. There, the sharp unseated overlay edge may tear into the tire, causing severe damage.
The unseated or separated overlay poses a more likely risk under “run flat” conditions. Vehicles are sometimes run with flat tires for short distances until the tire can be serviced. Under these circumstances, the tire sidewalls distort outward over the standard rim flange of the wheel, and spin relative to the wheel. The sharp peripheral edge of an overlay wrapped around the flange lip of the standard rim flange of the wheel may tear into the rubber tire causing severe damage.
Consequently, what is needed is an overlay that covers the entire outboard surface of the wheel including a wheel where the rim flange has been reduced to a minimum functional flange height or truncated by machining and the overlay is assembled to the wheel without wrapping around the flange lip of the rim flange of the wheel so as to not affect the aesthetics of the vehicle. Such an overlay is appropriately retained with an adhesive to the outboard surface of the wheel, wherein the peripheral flange of the overlay is preferably net located against the minimum functional flange height rim flange, or alternatively against a machined wheel or truncated rim flange of the wheel. This configuration will seal the interface between the overlay and the wheel, and ensure overlay and tire integrity under all operating and service conditions of the wheel, including tire installation and removal, radial load deflections, and “run flat” conditions.